JPH09326564A - Manufacture of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a circuit board where a wiring pattern and a conductive member can be electrically and surely connected together. SOLUTION: A circuit board 1 is formed of a laminate composed, of insulating boards, wherein a wiring pattern 3 is formed on the surface of the laminate or between the insulating boards. A through-hole 5 is provided to a point where the wiring patterns are required to be electrically connected together, and conductive member is filled in through-hole 5. In this case, a manufacturing process where a circuit board is formed is composed of a first process where a wiring pattern inside the through-hole 5 is surface-treated with coupling agent and a second process where conductive member is filled in the through-hole 5 where the wiring pattern is previously subjected to a surface treatment.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of manufacturing a circuit board. Conventionally, when a component is mounted on a printed circuit board, it has been usual to place the circuit component on the surface of the component, insert the lead of the circuit component into the through hole, and solder it. However, in recent years, the packaging density of circuit components has been improved, the wiring patterns have been miniaturized accordingly, and the number of pins of the circuit components has increased significantly. With the increase in the density of such circuit boards, printed circuit boards having three or more layers have been used, and multilayer circuit boards that are easy to manufacture are required.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing an example of the structure of a conventional circuit board. In the figure, reference numeral 1 denotes a circuit board, which is composed of a laminated body of three insulating substrates. Two
Is a wiring pattern (circuit pattern) formed on the front and back surfaces of the circuit board 1, 3 is a wiring pattern provided on an inner layer of the circuit board 1, and 4 is for electrical connection between the front surface and the back surface of the circuit board 1. It is a hardened body of a copper paste as a conductive member filled in the through hole opened in the. The hardened body 4 of the copper paste electrically connects the wiring patterns 2 and 3 between the front surface and the back surface of the circuit board 1, the outer layer, the inner layer, and the inner layer.

[0003]

In the above-mentioned conventional circuit board, the electrical connection of the wiring pattern between the front surface and the back surface of the circuit board and the outer layer, the inner layer and the inner layer is performed by curing the copper paste filled in the through hole. It depends on the body 4. However, the electrical connection between the wiring patterns 2 and 3 and the copper paste hardened body 4 cannot be said to be good, and there is a problem that the contact resistance becomes high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a circuit board which can establish a good and reliable electrical connection between a wiring pattern and a conductive member. I am trying.

[0005]

The present invention for solving the above-mentioned problems is a circuit board comprising a laminate of a plurality of insulating substrates, wherein a wiring pattern is provided on the surface of the laminate or between the plurality of insulating substrates. And a through hole is provided at a position where electrical connection is required between the wiring patterns, and the through hole is filled with a conductive member. It is characterized by comprising a first step of surface-treating with a coupling agent and a second step of surface-treating the wiring pattern in the through hole and then filling the conductive member into the through hole. .

According to the structure of the present invention, the through hole is filled with the conductive member after the surface treatment of the wiring pattern in the through hole is performed. Therefore, the contact resistance between the conductive member filled in the through hole and the wiring pattern in the through hole is reduced, and good and reliable electrical connection between the wiring pattern and the conductive member can be achieved.

In this case, a step of subjecting the wiring pattern in the through hole to a surface treatment with a coupling agent is performed after the processing of causing the wiring pattern in the through hole to protrude from the insulating substrate.

According to the structure of the present invention, since the wiring pattern is projected into the through hole, the contact area between the wiring pattern and the conductive member is increased, which is combined with the step of surface-treating the wiring pattern with a coupling agent. As a result, a better and more reliable electrical connection can be established between the wiring pattern and the conductive member.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart showing an embodiment of the method of the present invention. The present invention is a circuit board comprising a laminated body of a plurality of insulating substrates, wherein a wiring pattern is formed on the surface of the laminated body or between the plurality of insulating substrates, and electrical wiring is provided between the wiring patterns. In a circuit board in which a through hole is provided at a position where connection is required and the through hole is filled with a conductive member, a first step of surface-treating a wiring pattern in the through hole with a coupling agent; A second step of filling the through hole with the conductive member after the surface treatment of the wiring pattern in the hole is performed. By taking such a step, good and reliable electrical connection can be established between the wiring pattern and the conductive member.

FIG. 2 is a view showing an embodiment of a process for manufacturing a circuit board according to the method of the present invention, each showing a cross section. The same parts as those in FIG. 4 are designated by the same reference numerals. In FIG. 1A, 1 is a circuit board, which is composed of a laminated body of three insulating substrates. 3 is a wiring pattern (circuit pattern) provided on the inner layer of the circuit board 1, 6 is a copper foil formed on the front and back surfaces of the circuit board 1, and 5 is the circuit board 1.
It is a through hole opened between the front and back surfaces of. The through hole 5 is provided at a place where electrical connection is required between the copper foil 6 and the wiring patterns 3 and has a diameter of 0.5.
It is drilled with a through hole of about mm.
The circuit board 1 is composed of a laminated body of glass epoxy insulating substrates having a thickness of about 1.2 mm. The inner layer wiring pattern 3 has a thickness of about 35 μm, and the copper foil 6 formed on the front and back surfaces of the circuit board 1 has a thickness of about 35 μm to form a conductive layer.

(B) The wiring pattern and the copper foil in the through hole 5 are surface-treated with a coupling agent. Specifically, the conductive layer of the laminated body including the through holes 5 is stirred for 1 minute in a surface treatment solution prepared by diluting a titanium-based coupling agent (isopropyltriisostearoyl titanate) with hexane 100 times. Surface treatment is carried out by dipping, and the excess titanium coupling agent attached is washed with hexane.
dry. Reference numeral 10 in the figure shows the surface-treated region, which is indicated by a thick solid line.

The coupling agent used in the present invention is a material used to enhance the adhesiveness at the interface between glass, carbon fiber, metal, etc. and the polymer, and as a result, to improve the properties of the composite material. Well-known ones can be used. Examples include silane coupling agents such as vinyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, organotitanium-based coupling agents such as isopropyltriisostearoyl titanate, diisostearoylethylene titanate, and isopropylyltridodecylbenzenesulfonyl titanate. Other than the coupling agent, there are organoaluminum coupling agents, chromium coupling agents, organic phosphoric acid coupling agents, silyl peroxides and the like.

The surface treatment method used in the present invention can be performed by a known method without particular limitation. For example, after immersing in a diluted solution of the coupling agent, a method of drying and treating or a method of spraying by direct spraying,
Alternatively, there may be mentioned a primer method in which a condensate of a coupling agent or the like is diluted with a solvent and applied, and the solvent is dried to form a continuous film. Further, if necessary depending on the type of coupling agent, heat treatment may be performed after coating or after drying.

(C) The through hole 5 is filled with a copper paste as a curable conductive member. Specifically, it is filled with copper paste by a screen printing method and is heated in an air oven to 50
Curing is carried out under the conditions of ° C-30 minutes and 180 ° C-60 minutes. Reference numeral 11 in the figure is a cured body of copper paste. The composition of the copper paste includes, as a binder component, bisphenol A diglycidyl ether having an epoxy equivalent of 173 g / equivalent, 35 parts by weight of decyl glycidyl ether to 100 parts by weight of the bisphenol A diglycidyl ether, and novolak as a curing agent. Type phenolic resin 39 parts by weight and dendritic copper powder having an average particle size of 10.5 μm as copper powder were added in an amount of 360 parts by weight with respect to 100 parts by weight of the binder.
Further, 2.8 parts by weight of 2-ethyl-4-methylimidazole was added to 100 parts by weight of the binder, and the mixture was kneaded with a three-roll for 45 minutes to prepare the mixture.

With such a structure, the hardened body 11 of the copper paste and the wiring patterns of the outer and inner layers or the copper foil are electrically connected to each other through the surface treatment area 10, so that the contact resistance of the contact portion is increased. Can be reduced and good and reliable electrical connection can be achieved.

(D) The surface of the circuit board 1 composed of the conductive layer and the conductive member (cured body of copper paste) 11 is
Use No. 00 buff and No. 360 buff sequentially to grind smoothly.

(E) Next, an etching resist is laminated on the surface of the copper foil 6, exposed and developed to form a resist pattern, and after etching with ferric chloride, the etching resist is peeled off. , The wiring pattern 2 is formed. As a result, the wiring patterns 2 and 3 of the outer layer and the inner layer are electrically connected to each other via the hardened body 11 of the copper paste.

According to the present invention, the conductive member 11 is filled in the through hole 5 after the surface treatment of the wiring pattern in the through hole 5 is performed. Therefore, the conductive member 11 filled in the through hole 5 and the through hole 5
The contact resistance with the internal wiring pattern is reduced, and good and reliable electrical connection between the wiring pattern and the conductive member 11 can be achieved.

FIG. 3 is a diagram showing another embodiment of the process for manufacturing a circuit board according to the method of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. (A) A process of projecting the inner layer wiring pattern 3 in the through hole 5 and the copper foil 6 on the surface from the insulating substrate is performed.
Specifically, through hole 5 with concentrated sulfuric acid and fluorocarbon acid.
Wiring pattern 3 from the insulating substrate by melting the insulating substrate layer in
And the copper foil 6 is made to protrude by about 20 μm to 30 μm (etching back treatment).

(B) The wiring pattern 3 and the copper foil 6 projected from the insulating substrate in the step (a) are surface-treated with a coupling agent. Reference numeral 10 in the figure denotes the surface-treated area. The surface treatment process is the same as that shown in FIG. That is, specifically, the conductive layer of the laminate including the through holes 5 is immersed in a surface treatment solution prepared by diluting the titanium coupling agent 100 times with isopropanol for 1 minute while stirring to perform the surface treatment. Then, the excess titanium coupling agent attached is washed with isopropynol and dried.

(C) The through hole 5 is filled with a copper paste as a curable conductive member by a screen printing method, and then it is heated in an air oven at 50 ° C-30 minutes for 180 ° C-6.
It is cured under the condition of 0 minutes. According to this example embodiment,
The wiring pattern 3 and the copper foil 6 on the inner wall of the through hole 24
Since the copper paste 11 is filled in the through holes 5 after the protrusions of about μm to 26 m are further subjected to surface treatment, the hardened body 11 of the copper paste, the wiring patterns 3 and the copper foil are filled. Since the contact area with 6 is enlarged, the contact resistance can be reduced. Further, since the protrusion is surface-treated with a coupling agent, the contact between the hardened body 11 of the copper paste and each wiring pattern 3 and the copper foil 6 becomes good. Therefore, according to this embodiment, since the wiring pattern is projected into the through hole, the contact area between the wiring pattern and the conductive member is increased, and the wiring pattern is combined with the step of surface-treating with a coupling agent. As a result, a better and more reliable electrical connection can be established between the wiring pattern and the conductive member. The steps after (c) are the same as those shown in FIG.
By carrying out the same process as the process shown in (e) successively, a four-layer circuit board is realized.

In the above-described embodiment, the case where two layers are formed on each of the front surface and the back surface of the insulating substrate 1 in total of four layers has been taken as an example, but the second layer is formed on either the front surface or the back surface. You may do it. In this case, the circuit board has three layers.

According to the above-described embodiments, the case of realizing a circuit board having a total of four layers has been taken as an example. However,
The present invention is not limited to this, and includes a step of forming an insulating layer and a step of forming a wiring pattern on the insulating layer.
By providing an arbitrary number on the front surface and the back surface of the insulating substrate 1 or any one of the surfaces thereof, a circuit board having an arbitrary number of layers can be created.

[0024]

[Example] When the resistance value of the through hole was measured between the conductive patterns formed on the front and back of the obtained multilayer circuit board, it was 19 mΩ / hole on average. The resistance value of the through hole between the inner layers was measured and found to be 22 mΩ / hole. This circuit board is at -65 ° C
After 100 cycles of 30 minutes at 125 ° C for 30 minutes under the thermal test condition, the through-hole resistance value of the conductor pattern formed on the front and back of the circuit board was measured again. When the value was measured again, it was 25 mΩ / hole on average, and there was almost no change in the resistance value of the through hole before and after the test.

[0025]

As described above in detail, according to the present invention, there is provided a circuit board comprising a laminate of a plurality of insulating substrates, wherein wiring is provided on the surface of the laminate or between the plurality of insulating substrates. A pattern is formed, and through holes are provided at locations where electrical connection is required between the wiring patterns,
In a circuit board in which a conductive member is filled in the through holes, a first step of surface-treating a wiring pattern in the through holes with a coupling agent, and after performing a surface treatment of the wiring patterns in the through holes The second step of filling the through hole with the conductive member allows the through hole to be filled with the conductive member after the surface treatment of the wiring pattern in the through hole is performed. The contact resistance between the conductive member filled inside and the wiring pattern in the through hole is reduced, and good and reliable electrical connection between the wiring pattern and the conductive member can be achieved.

In this case, after the wiring pattern in the through hole is projected from the insulating substrate, the wiring pattern in the through hole is surface-treated with a coupling agent to form the wiring pattern. Since it is projected into the through hole, the contact area between the wiring pattern and the conductive member is large, and by combining it with the step of surface-treating the wiring pattern with a coupling agent, it is even better between the wiring pattern and the conductive member. It is possible to make a reliable electrical connection.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention.

FIG. 2 is a diagram showing an example of an embodiment of a manufacturing process of a circuit board according to the method of the present invention.

FIG. 3 is a diagram showing another embodiment of the manufacturing process of the circuit board by the method of the present invention.

FIG. 4 is a diagram showing a configuration example of a conventional circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Wiring pattern 3 Wiring pattern 10 Surface treatment area 11 Cured body of copper paste

Claims (2)

[Claims] 1. A circuit board comprising a laminated body of a plurality of insulating substrates, wherein a wiring pattern is formed on the surface of the laminated body or between the plurality of insulating substrates, and an electrical circuit is provided between the wiring patterns. A circuit board in which a through-hole is provided at a position where a static connection is required, and the through-hole is filled with a conductive member; a first step of surface-treating a wiring pattern in the through-hole with a coupling agent; A second step of filling the through hole with the conductive member after the surface treatment of the wiring pattern in the through hole is performed. 2. The step of subjecting the wiring pattern in the through hole to a surface treatment with a coupling agent after performing the processing of projecting the wiring pattern in the through hole from the insulating substrate. A method for manufacturing the circuit board described.